Companion object to StateStore that provides helper methods to create and retrieve stores
by their unique ids. In addition, when a SparkContext is active (i.e. SparkEnv.get is not null),
it also runs a periodic background task to do maintenance on the loaded stores. For each
store, it uses the StateStoreCoordinator to ensure whether the current loaded instance of
the store is the active instance. Accordingly, it either keeps it loaded and performs
maintenance, or unloads the store.
Companion object to StateStore that provides helper methods to create and retrieve stores by their unique ids. In addition, when a SparkContext is active (i.e. SparkEnv.get is not null), it also runs a periodic background task to do maintenance on the loaded stores. For each store, it uses the StateStoreCoordinator to ensure whether the current loaded instance of the store is the active instance. Accordingly, it either keeps it loaded and performs maintenance, or unloads the store.